Abstract
The processes by which a human acquired the ability to perceive visual form were investigated in a congenitally blind subject who gained sight through an operation performed at the age of 12. After the operation, she could identify motion, color, and 2-dimensional direction, and could also discriminate 2-dimensional size, but not forms (e.g., triangle, square, circle). The results may be summarized as follows : (1) When attempting to see the form on a board, the subject moved her head and for a board in her hands. (2) In her visual processes of identifying the form, she comparedsizes and/or directions of the form picked up by her head movement and/or the board movement with her internal knowledge, wherein the visual form image consisted of verbalized information about the sizes and/or directions of the form. On the other hand, the tactual form image consisted of the whole of the figure. (3) The reaction time was shortened, when the situation was changed from identification to discrimination.
